#include <iostream>

using std::cout;
using std::endl;

class NullPointer
{
public:
    void test1(int ix) 
    {   cout <<"ix:" << ix << endl;}

    void test2()
    {   cout << "test2()" << endl;  }

    static void test3()
    {   cout << "test3()" << endl;}

    void test4()
    {
        cout << "_ix:" << this->_ix << endl;
    }

private:
    int _ix;
};

int main()
{
    NullPointer * p1 = nullptr;
    p1->test1(10);//NullPointer::test1(p1, 10);
    p1->test2();//NullPointer::test2(p1);
    p1->test3();//NullPointer::test3();
    p1->test4();//this指针是空指针   NullPointer::test4(p1);

    return 0;
}

